A multiscale domain decomposition approach for chemical vapor deposition

We consider the chemical vapor deposition process on a trenched Si-substrate. To understand the process (e.g. the layer conformality) at the trench scale (microscale), we need solutions at both the trench and reactor scales (macroscale). Due to huge difference in the sizes of these scales, straightforward numerical computations are very challenging. To overcome this dif¿culty, we consider a multiscale approach by introducing an intermediate scale (mesoscale). We start with time-continuous model describing the transport processes and then perform time discretization. At each time step, using the ideas of domain decomposition inspired from [4], we provide an iterative coupling conditions for these three different scales. Using weak formulation for the time-discrete equations, we prove the convergence of this iterative scheme at each time-step. The approach also provides an alternative proof for the existence of the solutions for the time-discrete formulation

On the electrochemistry of an anode stack for all-solid-state 3D-integrated batteries

This paper will report on the electrochemical and material characterization of a potential planar anode stack for all-solid-state 3D-integrated batteries. The first element of the stack is the silicon substrate. On top of silicon, a Li diffusion barrier layer material is deposited in order to effectively shield the substrate from the battery stack. Several materials are investigated with conventional electrochemical techniques. The best candidates, sputtered and atomic layer deposited (ALD) TiN, are studied in more detail with ex situ X-ray diffraction (XRD) and the reaction mechanism of these materials with Li is discussed. The third element of the stack is the active anode material. Thin films of poly-Si are studied towards their thermodynamic and kinetic properties. Moreover, the growth of SEI layers on top of poly-Si anodes cycled in two liquid electrolytes has been investigated by means of ex situ SEM. Strikingly, when poly-Si is covered with a solid-state electrolyte, prolonged lifetime is found, enabling future 3D-integrated all-solid-state batteries

Origin of degradation in Si-based all-solid-state Li-Ion micro-batteries

\u3cp\u3eLike all rechargeable battery systems, conventional Li-ion batteries (LIB) inevitably suffer from capacity losses during operation. This also holds for all-solid-state LIB. In this contribution an in operando neutron depth profiling method is developed to investigate the degradation mechanism of all-solid-state, thin film Si–Li\u3csub\u3e3\u3c/sub\u3ePO\u3csub\u3e4\u3c/sub\u3e–LiCoO\u3csub\u3e2\u3c/sub\u3e batteries. Important aspects of the long-term degradation mechanisms are elucidated. It is found that the capacity losses in these thin film batteries are mainly related to lithium immobilization in the solid-state electrolyte, starting to grow at the anode/electrolyte interface during initial charging. The Li-immobilization layer in the electrolyte is induced by silicon penetration from the anode into the solid-state electrolyte and continues to grow at a lower rate during subsequent cycling. X-ray photoelectron spectroscopy depth profiling and transmission electron microscopy analyses confirm the formation of such immobilization layer, which favorably functions as an ionic conductor for lithium ions. As a result of the immobilization process, the amount of free moveable lithium ions is reduced, leading to the pronounced storage capacity decay. Insights gained from this research shed interesting light on the degradation mechanisms of thin film, all-solid-state LIB and facilitate potential interfacial modifications which finally will lead to substantially improved battery performance.\u3c/p\u3